The standard set of rules defined in Combinatory Categorial Grammar (CCG) fails to provide satisfactory analyses for a number of syntactic structures found in natural languages. These structures can be analyzed elegantly by augmenting CCG with a class of rules based on the combinator D (Curry and Feys, 1958). We show two ways to derive the D rules: one based on unary composition and the other based on a logical characterization of CCG’s rule base (Baldridge, 2002). We also show how Eisner’s (1996) normal form constraints follow from this logic, ensuring that the D rules do not lead to.
